Last year I travelled the s100 in the late mornings, and both times saw a martial not far from the s41 just before the Nsasane waterhole, it was overcast and not eagle flying weather. The kgalagadi is also excellent for martials, we always see at least half a dozen.

Whatever (according to BB): "You are correct but I don't want to admit it".

Happened in June this year at one of my favourite bird spots - Grootvlei on the back road to Shingwedzi (S50).

I was watching some grey heron and saddlebills in the water when a large eagle arrived and moved between various perches. A juvenile martial without a doubt.

It then settled in a tree where there was another young eagle - but what sort?

And far from being upset with each other, the marial definitely appeared to be encouraging the other young one to take its first flight. The pictures could be misinterpreted I suppose - they were definitely not fighting or angry or whatever.

Do eagles mix like this. Would one species try to fledge another. Or do very young martial look completely different (no book shows this so I don't think this is the explanation).

In nature these two birds would not interact no matter how young they are. Looking at the photos there appears to be a nest and I would suspect (might be wrong) that the nest belongs to the Tawny and he was defending it. Seeing that the Martial is not an adult the Tawny might have been a bit bolder and stood his ground. The Martial might not have shown aggression but rather curiosity and hense the appearance of playful interaction.
Any other thoughts ?

No idea of the answer, but it is a great sequence of pics, probably worth sending through to 50/50 in my humble opinion - they will also probably be able to track down the expert able to answer the riddle.

We do not inherit the Earth from our ancestors, we borrow it from our children

Ja ja! Satara is a great habitat for all sorts of raptors. thge open plain with scattered trees is perfect for martials and the likes. I have found the Orpen road very good for martials. Best sighting of one I had was on the Matjulu bridge near BnD in March. Perched right next to the bridge in a tree.